The renin-angiostensin-aldosterone (RAA) system has been suggested as a key factor in explaining different rates of hypertension between Caucasians and African-Americans. Previous work involving relatively small samples of study participants has resulted in conflicting results regarding this issue. Renin and aldosterone will be measured, along with potentially confounding factors, including sodium and potassium excretion, total body water, BMI, and various lifestyle-related factors (smoking, alcohol intake, etc.).